1. Field of the Invention
The present invention relates to an angle-adjusting device for a treadmill supporting frame, and more particularly, to a compact, low-cost and easy-to-use device.
2. Description of the Prior Art
The prior art of U.S. Pat. No. 5,607,375, as shown in FIG. 6, is the most well known angle-adjusting device for a treadmill supporting frame. This prior art includes an engaging member 11 fastened on the rear supporting rod 10, a plurality of stage type engaging bevel teeth 12 at the other end of the engaging member 11, a pivot 13 by which the pivoted plate 15 at the bottom of the frame 14 is pivoted, a supporting member 17 pivoted by a pivot 16 under the pivoted plate 15 and a spring 20 hooked between an axle pin 18 disposed at the bottom end of the supporting member 17 and an opposed axle pin 19 of the pivoted plate 15. At this time, any engaging bevel tooth 12 of the engaging member 11 is supported by the top portion 171 at the other end of the support member 17 and kept in position. Accordingly, in adjusting the sloping angle of the frame 14, it's only required to raise the frame 14 to allow the rear supporting rod 10 to fall down automatically due to its weight by means of the pivot 13. At this point, the engaging bevel tooth 12 at the other end of the engaging member 11 will be shift upwards to permit the next engaging bevel tooth 12 to be supported at the top portion 171 of the supporting member 17. Therefore, the supporting angle of the rear supporting rod 10 is changed so that the sloping angle of the frame 14 is also changed.
Though this conventional product is easy to use, its structure is complex and has too many components. Thus, the production cost is relatively high and it can't meet the economical and efficient requirement of the industry.